一、头文件、函数及说明

/* spinlock_t
源码位置 ： include/linux/spinlock_types.h
*/ 
typedef struct spinlock {union {struct raw_spinlock rlock;//实现见附A 1.1#ifdef CONFIG_DEBUG_LOCK_ALLOC
# define LOCK_PADSIZE (offsetof(struct raw_spinlock, dep_map))struct {u8 __padding[LOCK_PADSIZE];struct lockdep_map dep_map;};
#endif};
} spinlock_t;/*spin_lock_init()源码位置 ： include/linux/spinlock.h
*/
#define spin_lock_init(_lock)                           \
do {                                                    \spinlock_check(_lock);                          \raw_spin_lock_init(&(_lock)->rlock);            \
} while (0)/*spin_lock()源码位置 ： include/linux/spinlock.h
*/
static inline void spin_lock(spinlock_t *lock)
{raw_spin_lock(&lock->rlock);
}
/*spin_unlock()源码位置 ： include/linux/spinlock.h
*/
static inline void spin_unlock(spinlock_t *lock)
{raw_spin_unlock(&lock->rlock);
}

二 、代码举例（内核空间）

==支持在用户空间控制LED灯开和关，也支持按键对LED灯进行操作 ==

#include <linux/init.h>
#include <linux/module.h>
#include <linux/gpio.h>
#include <cfg_type.h>
#include <linux/interrupt.h>
#include <linux/fs.h>
#include <linux/miscdevice.h>
#include <asm/uaccess.h>
#include <linux/delay.h>
static int file_count_num=0;//记录文件打开次数
spinlock_t lock;//自旋锁对象；/*LED灯硬件信息*/
struct led_src {char *name;int   gpio;
};
struct led_src led_info[] = {{.name = "LED1",.gpio = PAD_GPIO_B +26},{.name = "LED2",.gpio = PAD_GPIO_C +11},{.name = "LED3",.gpio = PAD_GPIO_C +7},{.name = "LED4",.gpio = PAD_GPIO_C +12}
};/*按键硬件信息*/
struct btn_src {char *name ;int  gpio;
};
struct btn_src btn_info[] = {{.name = "BTN1",.gpio = PAD_GPIO_A +28},{.name = "BTN2",.gpio = PAD_GPIO_B +30},{.name = "BTN3",.gpio = PAD_GPIO_B +31},{.name = "BTN4",.gpio = PAD_GPIO_B +9}
};/*打开LED灯函数*/
static void led_on(unsigned long buf[4]){unsigned long *tmp_buf;tmp_buf = buf;if(gpio_get_value(led_info[tmp_buf[0]-1].gpio))gpio_set_value(led_info[tmp_buf[0] - 1 ].gpio,0);elseprintk("LED%ld灯已经是开启状态\n",tmp_buf[0]);
}/*关闭LED灯函数*/
static void led_off(unsigned long buf[4]){unsigned long *tmp_buf;tmp_buf = buf;if(gpio_get_value(led_info[tmp_buf[0] -1].gpio))printk("LED%ld灯已经是关闭状态\n",tmp_buf[0]);elsegpio_set_value(led_info[tmp_buf[0] - 1].gpio,1);
}/*LED灯状态信息函数）*/
static unsigned long * led_state(unsigned long buf[4]){int i = 0;unsigned long *tmp_buf;tmp_buf = buf;if(tmp_buf[0])tmp_buf[0] = gpio_get_value(led_info[tmp_buf[0] -1].gpio);elsefor(; i < ARRAY_SIZE(led_info);i ++)tmp_buf[i] = gpio_get_value(led_info[i].gpio);return buf;
}/*字符设备文件打开处理函数*/
static int led_open(struct inode * inode ,struct file * file){spin_lock(&lock);//使用自旋锁保存全局变量if(file_count_num){printk("字符设备文件已经被打开\n");spin_unlock(&lock);//如果设备已经被打开，在这里释放自旋锁；return -EBUSY;}file_count_num ++;printk("字符设备文件打开成功\n");spin_unlock(&lock);//释放自旋锁return 0;
}
/*字符设备打开关闭函数*/
static int led_close(struct inode * inode , struct file * file){spin_lock(&lock);//使用自旋锁保存全局变量file_count_num  = 0;printk("字符设备文件关闭\n");spin_unlock(&lock);//释放自旋锁return 0;
}/*ioctl（）函数底层处理方式*/
#define LED_ON    0X1000
#define LED_OFF   0X1001
#define LED_STATE 0X1002
long myioctl_func(struct file * open_file , unsigned int ucmd, unsigned long ubuf){int kcmd = ucmd;unsigned long kbuf[4];copy_from_user(kbuf,(unsigned long *) ubuf,sizeof(long) * 4);switch(kcmd){case  LED_ON :led_on(kbuf);break;case  LED_OFF :led_off(kbuf);break;case  LED_STATE :led_state(kbuf);copy_to_user((unsigned long *)ubuf,kbuf,sizeof(long) * 4);break;default :break;}return 0;
}/*定义文件操作接口*/
struct file_operations led_fops = {.owner          = THIS_MODULE,.open           = led_open,.release        = led_close,.unlocked_ioctl = myioctl_func
};/*定义混杂设备接口*/
struct miscdevice misc_fops = {.minor = MISC_DYNAMIC_MINOR,.name = "myled_drv",.fops = &led_fops
};/*中断处理函数*/
static irqreturn_t btn_irq_func(int irq,void * argv){struct btn_src *btn_irq = (struct btn_src *) argv;char btn_name[10];unsigned long  led_num[4];mdelay(5);strcpy(btn_name,btn_irq ->name);led_num[0] = btn_name[strlen(btn_name)-1] -'0';gpio_get_value(led_info[led_num[0] -1].gpio) ? \led_on(led_num) : led_off(led_num) ;printk("%s按键触发，%s状态为%s\n",btn_irq -> name,\led_info[led_num[0] -1].name,\gpio_get_value(led_info[led_num[0] -1].gpio) ? "关闭" : "开启");return IRQ_HANDLED;
}/*驱动模块加载函数*/
static int led_btn_misc_spin_init(void){int i = 0;for(; i < ARRAY_SIZE(led_info);i++){gpio_request(led_info[i].gpio,led_info[i].name);gpio_direction_output(led_info[i].gpio,1);gpio_request(btn_info[i].gpio,btn_info[i].name);gpio_direction_input(btn_info[i].gpio);request_irq(gpio_to_irq(btn_info[i].gpio),\btn_irq_func,IRQF_TRIGGER_RISING,\btn_info[i].name,&btn_info[i]);}misc_register(&misc_fops);//注册混杂设备对象spin_lock_init(&lock);//初始化自旋锁对象return 0;
}/*驱动模块卸载函数*/
static void led_btn_misc_spin_exit(void){int i = 0;for(; i < ARRAY_SIZE(led_info);i++){gpio_set_value(led_info[i].gpio,1);gpio_free(led_info[i].gpio);free_irq(gpio_to_irq(btn_info[i].gpio),&btn_info[i]);gpio_free(btn_info[i].gpio);}misc_deregister(&misc_fops);//释放混杂设备对象
}
module_init(led_btn_misc_spin_init);
module_exit(led_btn_misc_spin_exit);
MODULE_LICENSE("GPL");

三、代码举例（用户空间）

#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <string.h>#define LED_ON    0X1000
#define LED_OFF   0X1001
#define LED_STATE 0X1002
static void led_state(unsigned long led_num , unsigned long *buf){int i = 0;if(led_num)printf("led%d状态为%s\n",led_num,buf[0] ? "关闭" : "开启");elsefor(; i < 4 ; i ++)printf("led%d状态为%s\n",i,buf[i] ? "关闭" : "开启");
}
int main(int argc , char * argv[]){unsigned long  led_num = 0;int fp;unsigned int ucmd;unsigned long  ubuf[4];if((argc <3) || (argc > 4))goto err;if(argc == 4){led_num = strtoul(argv[3],NULL,0);if((led_num <0) || (led_num > 4))goto err_led_num;}if( ! strcmp(argv[2],"state"))ucmd = LED_STATE;else if((! strcmp(argv[2] , "on")) && (argc == 4))ucmd = LED_ON;else if((! strcmp(argv[2], "off"))  && (argc == 4))ucmd = LED_OFF;elsegoto err;fp = open(argv[1] , O_RDWR);if(fp < 0 )goto err_file;ubuf[0] = led_num;ioctl(fp,ucmd,ubuf);if(ucmd == LED_STATE)led_state(led_num,ubuf);sleep(30);//用于测试字符设备文件只能同时一个用户打开close(fp);return 0;
err :printf("命令错误：\n");printf("         comm <cdev_file> <state> [led_num]\n");printf("         comm <cdev_file> <on | off > <led_num>\n");return -1;err_led_num :printf("LED灯编号错误（1 ～ 4）；\n");return -1;err_file :printf("字符设备文件打开失败！\n");return -1;
}

四、测试

#加载驱动模块
/drivers/test # insmod myspin_led_btn.ko 
#开启LED1，并且后台运行30秒
/drivers/test # ./a /dev/myled_drv on 1 &
/drivers/test # [  828.536000] 字符设备文件打开成功
fp: 3 ,ucmd : 4096 , ubuf[0]:1
//程序没有结束前，通过按钮可以进行控制LED灯，
/drivers/test # [  833.015000] BTN2按键触发，LED2状态为开启
//上一个进程没有结束前，新的进程不能打开这个字符设备文件
/drivers/test # ./a /dev/myled_drv on 3
[  838.674000] 字符设备文件已经被打开
字符设备文件打开失败！
/drivers/test # 

附A 1.1

//源码位置： include/linux/spinlock_types.h
typedef struct raw_spinlock {arch_spinlock_t raw_lock;//实现见：附A 1.1.1
#ifdef CONFIG_GENERIC_LOCKBREAKunsigned int break_lock;
#endif
#ifdef CONFIG_DEBUG_SPINLOCKunsigned int magic, owner_cpu;void *owner;
#endif
#ifdef CONFIG_DEBUG_LOCK_ALLOCstruct lockdep_map dep_map;
#endif
} raw_spinlock_t;

附A 1.1.1

//源码位置：arch/arm/inclde/asm/spinlock_types.h
typedef struct {volatile unsigned int lock;
} arch_spinlock_t;